The present invention relates to devices used in the pipeline construction industry. More particularly, this invention relates to devices used to join the plain ends of pipe, as well as certain other ends of pipe.
Generally speaking, in constructing a pipeline, the ends of two pieces of pipe are axially joined to form a single conduit that is used to transport materials from one point to another. Often times, the materials being transported are fluid or gaseous in nature, and, particularly in those circumstances, it is desired that the pipeline be impervious to leaks. In order to accomplish that goal, and to achieve other objectives which will be herein described, those skilled in the business of pipe and pipeline construction are constantly in search of improved means for securing the joints formed by connecting the ends of pipe together.
There are numerous methods currently in use by those in the pipe and pipeline construction industry to obtain a secure joint. These methods employ different types of components and also can be distinguished by the various ways in which such components are employed. The selection of these different methods will usually depend on the overall design requirements of the pipeline. For instant, as mentioned previously, one important design requirement exists when it is desired that the pipe joints be sealed such that the material being transported within the pipeline can not escape and, conversely, foreign materials are prevented from entering the pipeline.
Another important design requirement exists when it becomes necessary to join the pipe components in a restrained manner. This is usually desired in order to prevent the pipe components from separating due to thrust forces that often occur when the pipeline is subjected to internal pressure, and sometimes, when earth tremors or other external events occur. Still another objective is to make assembly of the pipe joints as simple, economical and reliable as possible.
One current method for connecting pipe together employs the use of flanged fittings and gaskets. These are typical components in rigid piping systems, particularly above-ground systems such as water filtration plants, sewage disposal plants, wastewater treatment plants, pumping stations and chemical plants. Often times, the flanged fitting is threaded directly onto the pipe. This is accomplished by threading the plain end of a pipe (sometimes referred to as the spigot end) and threading a compatibly sized flanged fitting. The threaded flanged fitting is then machine-tightened onto the spigot end of the pipe and is often then transported to the field in this joined condition. In addition, it is common in the industry for the pipe and flanged fitting to have been xe2x80x9cfacedxe2x80x9d after proper tightening of the flanged fitting on the pipe. This is done by excising the portion of the threaded pipe that extends from the face of the flanged fitting such that the face of the flanged fitting is flush with the spigot end of the pipe. The threaded flanged pipe is then connected to another flanged pipe, usually by bolting means. In order to obtain a leak-free joint, a gasket is often used between the faces of the two flanged fittings.
The use of threaded flanged fittings presents several limitations as will now be discussed. The threaded flanged fitting is custom machined to accommodate the exact diameter of the pipe and to provide a smooth surface across the end of the pipe and the face of the flanged fitting. Also, extremely high torques are required to tighten properly the flanged fitting onto the threaded pipe. Consequently, one major limitation of this system is that preparation of the flanged fitting and pipe requires sophisticated machinery not usually available on-site where the finished component will be assembled and installed. If assembled at the pipe manufacturing facility before shipment, the presence of the flanged fitting militates against efficient and space-saving packing and reduces the amount of pipe components which can be transported.
In addition, to assure a proper seal, it is important for the threaded portion of the flanged fitting and pipe to be cleaned of all foreign material such as dirt, sand, grit or rust. The presence of foreign materials such as rust can also increase the amount of torque required to install the flanged fitting onto the pipe. Thus, manufacturing and assembling threaded flanged fittings and threaded pipe is very difficult in the field. Still another limitation of this system is that threaded pipe and threaded flanged fittings are individually mated, and the flanged fittings are not interchangeable. Still another limitation of threaded flanged fitting systems is that the pipe walls must be of substantially greater thickness in order to accommodate the threading which will be machined onto its exterior surface.
An alternative method for joining pipe uses unthreaded flanged fittings which are of appropriate diameter and which are fitted onto pipe ends in facing relationship to one another. As with the threaded flanged fitting, a gasket is often deployed between the faces of the flanged fittings to obtain a sealed joint. This is usually accomplished by bolting the flanged fittings together. In order to secure the flanged fitting to the pipe ends, set screws are inserted radially through the collar of the flange into the exterior surface of the pipe ends. One such example of this type of apparatus is disclosed in U.S. Pat. No. 4,480,861, issued Nov. 6, 1984, to Frank E. Cann.
Although the device disclosed by Cann solves some of the problems presented by use of a threaded flanged fitting, it is not without problems of its own. For instance, the flanged fitting in Cann""s device must be mated to one another and therefore limits the choices for joining pipe by those in the field. In addition, as those skilled in the art will appreciate, those assembling the flanged fitting in Cann""s device must be skilled in recognizing the extent to which the set screws should be tightened. Unless care is used in tightening the set screws, they can often damage and even puncture the pipe end. Conversely, if not sufficiently tightened, the set screws used in Cann""s device will cause the flanged fitting to become unstable or dislodged altogether.
A second common method for connecting the ends of pipe involves inserting the spigot end of one pipe into the expanded end of a second pipe the interior profile of which has been specially fabricated to form a socket (the expanded end sometimes being referred to as the xe2x80x9cbell endxe2x80x9d). The bell end is sized to accommodate the spigot end of the pipe to be received. The connection obtained by this method is also known in the industry as a xe2x80x9cpush-on joint.xe2x80x9d
There are several methods used to seal and/or secure the push-on joint. One such method involves inserting a fitted gasket within an annular recess formed within the throat of the socket of the bell. On such gasket is described in U.S. Pat. No. 2,953,398, issued Sep. 20, 1960, to L. Haugen and C. Henrikson. After the gasket is inserted into the annular recess of the socket, the spigot is aligned and forced through the gasket into the bottom of the socket, thereby compressing the gasket and sealing the two pipe ends together.
In order to restrain the spigot within the bell, a specially designed gasket is sometimes used. One such gasket employs stainless steel locking segments vulcanized circumferentially into the gasket as described in U.S. Pat. Nos. 5,295,697 and 5,464,228, issued to J. Weber and L. Jones on Mar. 22, 1994 and Nov. 5, 1995, respectively. The locking segments extend from the interior surface of the gasket, away from the interior surface of the bell end, such that they grip the spigot end of the inserted pipe when the pipeline is subjected to internal pressures.
Still another common method for connecting pipe is sometimes referred to as mechanical joint pipe. The bell end of a pipe has a flanged portion cast on it. The spigot end of a second pipe is fitted with a slidable gland fitting and a gasket that is conically shaped such that one face of the gasket is diametrically larger than the second face of the gasket. The conically shaped gasket is positioned between the gland fitting and the spigot end of the pipe with the smaller, second face of the gasket being closer to the spigot end than the larger, first face of the gasket. The gland fitting has a plurality of apertures for receiving standard bolts. The gland fitting also has an integrally formed, protruding lip which encircles the face of the gland fitting at its inside diameter such that the lip is adjacent to the surface of the pipe and faces the spigot end of the pipe when the gland fitting is positioned on the pipe. The face of the flanged portion has a tapered notch designed to receive the conically-shaped gasket when the spigot end is inserted into the bell. The joint is formed when the spigot is axially inserted into the bell, and the gland fitting and the flanged portion are bolted together, causing the lip of the gland fitting to compress the gasket thus sealing the two pipe pieces. Examples of this type of apparatus is disclosed in U.S. Pat. No. 5,398,980, issued Mar. 21, 1995, to T. Hunter, O. Jackson and M. Pannell; in U.S. Pat. No. 4,878,698, issued Nov. 7, 1995, to R. Gilchrist; and in U.S. Pat. No. 2,832,615, issued Apr. 29, 1958 to A. Summers. Although each of these devices embodies a system that purports to couple pipes in sealing relation to one another, each system requires that conventional metal pipe bells be used, thus limiting the flexibility of those assembling the pipeline, and increasing the transportation and storage difficulties incurred by the pipeline assemblers. There is, consequently, a need in the industry for a compact, lightweight, easy to install pipe fitting which converts plain pipe to various pipe joint configurations such as a flanged or a mechanical joint.
The present invention embodies a significant advancement in the field of pipe manufacture and assembly. The new fitting can be used on standard pipe which needs no special preparation such as welding or threading prior to attachment. As a one-piece pipe fitting, the flanged pipe fitting described herein is simple to manufacture (and therefore economical), is easy to assemble in the field, and is equally or more stable and secure than other alternatives now available. By accomplishing these and other objectives, the disclosed flanged pipe fitting offers those in the business of constructing pipelines with a valuable new component for connecting pipe ends.
The improvements described herein have been achieved in a new flanged pipe fitting to be used in receiving and joining a first pipe and a second pipe. It will be appreciated by those skilled in the art that the fitting is best utilized to mate with a compatible pipe fitting such as a gland fitting attached to another pipe in order to obtain the coupling properties of a standard mechanical joint. The flanged pipe fitting disclosed is a one-piece, tubular casting having an internal chamber and first and second openings at the first and second extremities, respectively, of said tubular casting. The tubular casting is fabricated such that the internal chamber forms a double socket for receiving the spigot ends of pipes. This double socket configuration is accomplished by fabricating an inwardly protruding, annular ridge on the interior surface of the tubular casting and at a point roughly equidistant from the two extremities of the tubular casting thereby forming two socket separated by a cylindrical opening of slightly smaller diameter than the diameter of the spigot ends of pipes to be inserted through the first and second openings at the extremities of the tubular casting.
The surface of the internal chamber is further fabricated such that the throat of at least one of the two sockets formed therein contains an annularly recessed channel designed to receive an internal, cylindrical gasket for sealing, and where desired, for restraining purposes when used to form a push-on joint. One such gasket is disclosed in U.S. Pat. No. 5,464,228.
The tubular casting has a shoulder, or flanged portion, extending radially outward at a substantially right angle to form a cylindrical face encircling the tubular casting. In the preferred embodiment, the flanged portion is located at the extremity of the tubular casting that is farthest from the annular recessed channel, thereby facilitating coupling with the second pipe to be inserted into opening of the tubular casting opposite from the end having the annular recessed channel. The external face of the flanged portion has fabricated at its internal diameter a notch that is tapered perpendicularly from the external face of the flanged portion. It will be appreciated that, so configured, the notch is designed to receive a complementally-shaped gasket used to form mechanical joint pipe when the flanged portion is mated with an appropriately sized gland fitting slidably attached along with the gasket to the spigot end of the second pipe. In a preferred embodiment, the face of the flanged portion has a plurality of apertures for receiving bolts or other connecting means in order to secure the fitting to the appropriately sized and positioned gland. It will be understood by those in the industry that alternative means exist for securing pipe fittings together, and the present invention is not restricted to the use of bolts and bolt apertures.
The new pipe fitting facilitates connections between pipe in the field without the need for sophisticated and time-consuming machining. Also, because the ridge and the recessed channel are fabricated within the new flange component before the joint is assembled, the location of the gasket and the extent to which the spigot must be inserted into the flange component is predetermined, thus eliminating the need for making precise measurements as is required by the invention disclosed by U.S. Pat. No. 3,589,750, issued Jun. 29, 1971 to P. Dunmire. These same features of the present invention also reduce substantially the possibility that the gasket will be displaced or damaged during assembly as is the case with Dunmire. Thus, the instant invention provides a significant improvement over current devices because it is makes assembly of pipeline more efficient, economical and error-free.